Probe May Hit U.K. Bank's Clean Image

LONDON—Last week, Standard Chartered PLC Chief Executive Peter Sands told analysts that "our culture and values are our first and last line of defense."

On Tuesday, allegations by a New York financial regulator that the Asian-focused U.K.-based lender hid illegal Iranian transactions seemed to breach that line. Shares plunged 16% on Tuesday, adding to Monday's 6.2% slide.